Treatment of cashew nut shell liquid



Patented Dec. 3, 1940 UNITED STATES PATENT caries Mortimer '1. Harvey, East Orange, N. 3., assisnor to The Hanoi Corporation, a corporation oi New Jersey No Drawing.

7 Claims.

The present invention relates to new compositions of matter and to methods and steps of making and using the same; and the present invention relates, moreparticularly, to new chemical compounds and derivatives thereof prepared from cashew nut shell liquid and to methods and steps for making and using the same.

Cashew nut shell liquid is described in the literature as consisting of about ninety'per cent of anacardic acid, CasHasOa and about ten per cent oi. cardol, Casi-15204, with very small tractlonal percentages of other materials.

According to the present invention, the cashew nut shell liquid is distilled at a greatly reduced pressure or in a stream of steam at atmospheric pressure to produce a compound having a molecular weight 01. 288, a boiling point of 225 C. at about 10 millimeters oi mercury, an empirical formula 01 CscHsaO, and a probable structural iormula oi C14H27CsH4OI-I. Characteristics and reactions indicate that this compound is a phenol with all or part of the CmI-Imatoms together as one radical in the meta position with respect to the -OH radical and with one unsaturated bon somewhere in the C14H27' atoms. This production of the new compound apparently takes place by the breaking down of the anacardic acid. Hereinafter, the new compound is called Cardanol.

when cashew nut shell liquid is distilled in air at normal pressure it is cracked into a number 01 compounds, including cardanol, having vari-' of my copending application Serial Number 489,-

, 484, filed October 17, 1980, and allowed August 7, 1933 and issued as Patent Number 1,950,085, issued March 6, 1934. v

However, when cashew nut shell liquid is distilled at a reduced pressure of about ten millimeters of mercury the cardanol comes over at a constant boiling point oi'about 225' C. with a very little amount of other compounds. Whenthe cardanol itself is distilled at normal pressure Application November 5, 1937, Serial No. 172,998

the boiling point of about 360 C. is constant and when it is distilled at ten millimeters of mercury the boiling point oi about 225 C. is constant. 1

In the distillation of cardanol in air a small amountoi darkening compounds is formed it the hot cardanol or vapors thereof come in contact with the air. When the cardanol is distilled tually in the form of an emulsion, the water of the condensed steam being dispersed in the new compound.

Due to conditions oi removing cashew nut shell liquid from the cashew nut shells, the proportion '01 cardanol obtained from a given amount of cashew nut shell liquid varies with the condition of the cashew nut shell liquid. That is to say, in all present commercial methods of obtaining cashew nut shell liquid from the cashew nuts heat is used, either to char or carbonize the shells for opening them or ior expelling the shell liquid from the shells, and the degrees of temperature at which these methods are carried out are such that decomposition otthe cashew nut shell ocours with the production of compounds, such as catechol, which distill over with the cardanol and Y which turn dark on exposure to the light. This is a great disadvantage because most of the uses to which cardanol are put require a light color in the final product, ior' example, in coatings,

varnishes, molded compositions, bottlecap paper,

electrical insulation, and so on. Further, the greater the degree of purity of the cardanol the greater is the suitability-oi the product for its Naturally, the amount oi cardanol obtainable from cashew nut shell liquid dependsupon the conditions to which the cashew nut shell. liquid has been subjected previous to its treatment to i obtain cardanol, and more cardanol is obtainable from cashew nut shell liquid which is extracted i from the nuts at low temperature than from cashew nut shell liquid which has been exces sively' heated. From low temperature extracted cashew. nut shell liquid the proportion of cardano] can be as high as 70% or more while from cashew nut shell liquid obtained by some methods stillin use the proportion is as low as 40 to Y According to the present. invention, this disadvantage is overcome either by obtaining the cashew nut shell. liquid at normal temperature as 2 by solvent extraction or by keeping the nuts at 1 a comparatively low temperature when heating to expellthe shell liquid, for example, at below 200 C.; also, the diiiiculty is overcome by changing the darkening compounds which go over with the cardanol into compounds which will not go over with it. These darkening compounds can be saturated to produce compounds which will not distill over at the temperatures at which cardanol is distilled. This I do by blowing air. oxygen, or hydrogen through the cashew nut shell liquid before it is distilled to take of! cardanol or by blowing the cardanolwiththese same materials before it is redistilled for purification,- this blowing being done with the cashew nut shell liquid or the cardanol on the alkaline side or with a catalyst such as copper-nickel for the hydrogen.

Illustrative examples of methods of preparing cardanol are given below together with descriptions of these materials and statements or their ture of about 165 C. The expelled shell liquid will mingle with the liquid of the bath and for this reason the liquid of the bath should be in a pure state, obtained, for example, by either the extraction or expulsion method just descrbed.

The cashew nut shell liquid obtained at a low temperature in this manner is distilled with steam at about 270 C. through a condenser at which temperature cardanol comes'over with the water 0! the condensed steam emulsified therein, the water being the dispersed phase. Upon standing most of the emulsion breaks, but heat is applied to about 90 C. to completely break the emulsionJafter which the cardanol and the water are separated. When it is so desired, the cardailol is further purified by distillingat the re- 4 cashew nut shell liquid which is obtained by' duced pressure. of aboutten millimeters of mercury.

Also, the cardanol is obtained from the cashew nut shell liquid obtained at low temperature-by one or more distillations at about ten millimeters.

of mercury, the number of distillations being determined by the degree of purity desired in the cardanol.v v

2. When cardanol is to be prepared. from some of the commercial methods still in use and in which excessive heating is employed to expel the shell liquid from the nuts, it contains compounds which contain active unsaturated bonds and which turn dark upon exposure to .the light, such as catechol, for example. These are broken oil from the cashew nut shells by the excessive heating. To obtain cardanol which is free of these. darkening compounds the methods of steam distillation and/or of distillation at ten millimeters of mercury, as above described,

are used, but previous to one or more of the distillation steps the cashew nut shell liquid or the cardanol is blown withair, oxygen, hydrogen or other suitable gas to saturate the unsaturated bonds and to obtain compounds which have higher boiling points than the cardanol and which do not go over with the cardanol when should be only to a slight degree.

the latter is distilled. This blowing is done on the alkaline side for which caustic soda in amount about one to two per cent of the weight of the cashew-nut shell liquid orcardanol is added before the blowing is begun.- Examples of time and temperature for this blowing are for about two or three hours at about to 'C., but other periods and temperatures can be employed. Ammonia and potassium hydroxide are other illustrative examples of materials for putting the material on the alkaline side.

3. To a given weight of raw cashew nut shell liquid from about one-half per cent to about two per cent loy weight of concentrated sulphuric acid are added with about an equal volume of 'water and stirred in and the mixture heated to about 325 F. under a reflux condenser andcooled, to precipitatesalts of metals naturally occurring in cashew nut shell liquid and leaving the cashew nut shell liquid in the liquid condition, that is the polymerization, if any This material is thenready for distillation under vacuum or with steam in the manner above described ior the purpose of obtaining cardanol and distillation residue in the manner .above described. Various equivalents of sulphuric acid set forth above and in addition thereto alkyl sulphates such as di-ethyl sulphate and mono-ethyl acid sulphate and the corresponding other alkyl sulphates can be used in place of or in addition to the concentrated sulphuric acid. In one case one per cent by weight of concentrated sulphuric acid and one per cent by weight of di-ethyl sulphate are added to a given weight of raw cashew nut shell liquid and heated in the manner above describedfor obtaining the treated cashew nut shell liquid suitable for distillation according to the present invention. In such and similar cases water is not used for diluting the sulphuric acid because the alkyl sulphate such as di-ethyl sulphate serves this purpose and avoids the necessity of removing the water to permit the action of the treating agent.

Methods and materials for the treatment of cashew nut shell liquid to precipitate salts therefrom and to produce a degree of polymerization when desired are shown'in Patent 2,067,919, is-

, sued January 19, 1937, to Harvey and Damltz,

and also in application Ser. No. [09,470 of S. Y Caplan.

In addition to the alkyl sulphates and mono-' alkyl and sulphates cited above as equivalents for sulphuric acid in the precipitation of metals from cashew nut shell liquid and in the poly-' merization of cashew nut shell liquid the 101- lowing can be used, either alone or in mixtures of two or more or them, (including the sulphuric 1 acid and the equivalents set forth above): by-

drochloric acid, phosphorous oxychloride, zinc chlorine, stannic chloride, aluminum chloride and phosphoric acid. V g

Metals occurring, naturally in cashew nut shell liquid, either in chemical combinations or in the uncombined state, include, among others, sodium, potassium, calcium, magnesium, iron and lead.

It is to be understood that the metals and salts precipitated from the cashew nut shell liquid can be removed therefrom by means oI- a centrifuge or a filter press or other suitable means or methods.

When cashew nut shell liquid is treated with concentrated sulphuric acid or its equivalents such as is set forth above or in said patent .or

in said copending application of Caplan and par ticuiarly when the salts are entirely removed therefrom before the cashew nut shell liquid is distilled, then the distillate is lighter in color and a higher yield is obtained. The higher yield is obtainable because heat polymerization or thickening in the still is retarded or reduced so that the higher percentage of distillate is ob tained before the residue thickens up to a condition in which it is a rubber-like solid when cooled to normal temperatures. This is particularly true when the 'steam distillation method is used. for example, at a temperature of between about 250 F. and 300 F.

Another method for saturating the darkening compounds before one of the distilling steps is to heat the cashew nut shell liquid or cardanol with an oxidizing agent such for example as sodium perborate. About one or two per cent of the weight of the 'cashewnut shell liquid or cardanol in sodium perborate, ,and at. about 270 C. for about two to three hours are examples of amount, temperature and time of heating. I

Another method or. getting cardanol free 'of darkening compounds is to wash the cashew nut shell liquid or the cardanol with water, for ex-.'

ample, in scrubbing towers or by shaking with water and separating the cashew nut shell liquid or cardanol from the water solution of the dark ening compounds. This washing can be followed by a distillation step, if desired or required as in the distillation of the cashew nut shell liquid or i for further purification of the cardanol.

Characteristics of cardanol Uses of cardanol Cardanol is useiul for making coatings such as paints, varnishes, lacquers, and so on, for impregnatingcompounds, for molded compounds and these products are also highly suitable for elec., trical insulation, for chemical and water and moisture proofings. with formaldehyde, hexamethylene .tetramine, paraformaldehyde, paint and varnish driers such as manganese resinate, lead oxides including litharge, metal-organic driers such as cobalt acetate and copper oleate, and other reactions such as are shown for cashew nut-shell liquid reactions in my patents listed below, to which reference is hereby made. The present invention is an improvement on the inventions disclosed in these patents and the products of cardanol have further advantages than the cashew nut shell liquid itself, for example, the cardanolcresol-formaldehyde condensation products are soluble to a greater extent in linseed and Chinawood oils than are the cashew nut shell liquidcresol-formaldehyde condensation products; cardanolis more effective as a solvent and plasticiser for cellulose esters such as nitro-cellulose, cellulose acetate and for the latter, known to be difllcultly plastieised, it is a very good plasticiser.

Cardanol can be reacted Following is a list 01 patents issued to me and cited to give examples of the application of products of the invention: Patents Nos. 1,725,791 to 1,725,797, inclusive, issued August 27, 1929;

1,771,785 and 1,771,786 issued July 29, 1930; 5

1,819,416 issued August 18, 1931; 1,838,070 to 1,838,077, inclusive, issued December 22, 1931; 1,921,292 and 1,931,293 issued August 8, 1933; 1,939,301 issued December 12, 1933: and 1,939,773 issued December 19, 1933. l0 This is a continuation in part of my copendlng application Ser. No. 7933M flied December 21, 1933, and issued as Patent 2,0983% on Novem-, ber 9, 1937, which latter is a continuation in part of my application Ser. No. ceases filed October 17, 1930, and issued as Patent No. 1,950,085 on March 6, 193a.

Having thus described my invention, what I claim as new and desire to protect by Letters Pat is:

1. The method which comprises the step of heating cashew nut shell liquid with an agent having the characteristic of polymerizing cashew nut shell liquid when heated therewith, said step being conducted until a thickening of the cashew D nut shell liquid is achieved and being discontinued at a point at which the treated cashew nut shell liquid is still liquid at normal temperature, and the subsequent step of destructively distilling the thickened cashew nut shell liquid under con- 39 ditions to obtain a phenol having an unsaturated. hydrocarbon substituent having about fourteen. carbon atoms, which phenol has a boiling point of about 225 C. at about ten millimeters of mercury.

2. The method which comprises the step of heating cew nut shell liquid with an agent having the characteristic of polymerizing cashew nut shell liquid when heated therewith, said stop being conducted until a thickening of the cashew g nut shell liquid is achieved and being discontim ued at a point at which the treated cashew nut shell liquid is still liquid at normal temperature, and the suuent step of destructively distilling the thickened cashew nut shell liquid with'steam as at atmospheric pressure to obtain a phenol having an unsaturated hydrocarbon substituent having about fourteen carbon atoms, which phenol has a boiling point of about 225 C. at about tenmill'imeters of mercury. 3. The method which comprises the step of heating cashew nut. shell liquid with an agent having the characteristic of polymerizing cashew nut shell liquid when heated therewith, said step being conducted until a thickening of the cashew nut shell liquid is achieved and being discontinneed at a point at which the treated cashew nut shell liquid is still liquid at normal temperature, and the subsequent step of destructivelydistilling the thickened cashew nut shell liquid at a presso sure in the neighborhood of about ten millimeters of mercury to obtain a phenol having an unsaturated hydrocarbon substituent having about fourteen, carbon atoms, which phenol has a boiling point bf about 225 C. at about ten millimeters of mercury.

4. The method which comprises removing the metals occurring naturally in cashew nut shell liquid'by heating cashew nut shell liquid with an agent having an inorganic negative radicle which will combine with said metals and subsequently destructively distilling to obtains. phenol which has an unsaturated side chain and which has a boiling point of about 225 C. at a pressure of about ten, millimeters of mercury.

5. The method which comprises removing the no m l p l l and h Subsequent, of

metals occurring naturally in cashew nut shell liquid by heating-cashew nut shell liquid with an agent having an inorganic negative radicle which will combine with said metals and destructively distilling at a pressure in theneighborhood 01 ten millimeters of mercury.

6. The method which comprises'heating cashew nut shell liquid with material selected Iromthe group consisting of sulphuric acid, dialkyl sulphate, and monoalkyl acid sulphate until athickening or the cashew nut shell liquid is achieved and discontinued at a point at which ,the so treated 'cashew nut shell liquid is still a liquid at destructively distilling the said sotreated cashew nut shell liquidto obtain a phenol having an unsaturated hydrocarbon substituent having about I 7. The method which comprises precipitating,

metals occurring naturally in cashew nut shell liquid by heating cashew nut shell liquid with an agent having an inorganic negative radicle which n will combine with said metals and destructively distilling the so treated cashew nut shell liquid with steam.

" deem T. 

